Fiber-reinforced sandwich panel

ABSTRACT

The present invention may be embodied in a sandwich panel having first and second face panels each panel having a first predetermined thickness and being formed of a fiber-reinforced cementitious material. The sandwich panel further includes support frame for supporting the first and second face panels in a spaced apart configuration. The support frame is formed of a fiber reinforced cementitious material that is continuous with the cementitious material of the first and second face panels. Blocks of rigid insulation are embedded in the sandwich panel for defining a structure of the support frame.

This application is a continuation-in-part of application Ser. No.09/993,374 filed on Nov. 14, 2001, the contents of which areincorporated herein by reference in their entirety.

FIELD OF THE INVENTION

The present invention relates to prefabricated structures, and moreparticularly, to fiber reinforced wall panels for ease of manufacture ofprefabricated structures that can be constructed.

BACKGROUND OF THE INVENTION

Walls of residential and public buildings are generally expected tocover as large an area as possible with as minimum a structural weightas possible. Also, walls are expected to possess proper load bearingcapacity, be economical with respect to the combination of constructionlabor and material costs and on-going maintenance costs, and to beadapted for prefabrication and for use in mounted constructions.Load-bearing concrete walls are generally thick, heavy, and difficult totransport. Also, an uninsulated concrete wall generally has a poor heatinsulation value and increasing the insulation value of the concretewall may be problematic.

Wood walls are lightweight, however, they are limited in strength. Ininstances where a wall is used as a primary or secondary support member,problems occur due to large deflections/vibrations in the wall, poorfire rating, and poor thermal and acoustic properties. Reinforcing woodwalls with concrete can make up for the limited strength of wood floors;however, traditional concrete walls are heavy and labor intensive andexperience problems due to crack control (flexure, shrinkage); theyrequire steel reinforcement with a minimum slab thickness.

To provide a wall with improved strength and deflection characteristics,composite materials have been used. However, to insure proper acousticcharacteristics, composite wall systems often employed more concretethan would otherwise be necessary to insulate an area from soundvibrations. This of course increases the dead weight of such walls, addsto construction labor and material costs, and requires increased shoringwhile the concrete is curing. Shoring adds yet further to wallconstruction cost and time. Excess concrete may also require that thebuilding be built on stronger foundations and have a strongersuperstructure. In some areas, ground or soil conditions may militateagainst such heavier buildings. Also, higher gage joists and strongerbeams and columns are required to support the heavier walls.Accordingly, fewer levels can be built in a building of a given weight.

Accordingly, there exists a need for a lightweight and relativelylow-cost prefabricated structure for competing in markets preferringconcrete structures. The present invention satisfies these needs.

SUMMARY OF THE INVENTION

The present invention is embodied in a fiber-reinforced sandwich paneland a unique composition for the manufacture of prefabricated buildings.The sandwich panel includes first and second face panels, a supportframe, and embedded insulation. Each of the first and second face panelshas a first predetermined thickness and is formed of a fiber-reinforcedcementitious material. The support frame supports the first and secondface panels in a spaced apart configuration. The support frame is formedof a fiber-reinforced cementitious material that is continuous with thecementitious material of the first and second face panels. Various mixdesigns are possible for the cementitious material. The block ofembedded insulation defines a structure of the support frame.

The support frame is formed of a fiber-reinforced cementitious materialthat is continuous with the cementitious material of the first andsecond face panels. The block of embedded insulation defines a structureof the support frame. The insulation block may be rigid.

In more detailed features of the invention, the sandwich panel may havea height greater than 4 feet, a width greater than about 4 feet, and athickness between about 2.5 and 8 inches. The thickness of the firstpanel may be between about 0.25 inches and 2.0 inches, and the thicknessof the second panel likewise may be between about 0.25 inches and 2.0inches. The support frame may have an upper border beam, a lower borderbeam, and first and second border beams that encompass the insulation.The support frame may further include one or more ribs that have alength extending between the lower border beam and the upper borderbeam, and that are substantially parallel with the first and second endbeams. The ribs may couple the first and second face panels along thelength of the ribs. Each of the beams may have a width of between about2-6 inches, and each of the ribs may have a width of between about 2-6inches. Due to the fiber-reinforcement, the tensile strength of thecementitious material is increased, thereby eliminating the need forsteel reinforcing rods; however, though it is not necessary, each borderbeam may be further strengthened by reinforcing bar. The cementitiousmaterial may have a composition, by weight before cure, of between about19% and about 41% Portland cement, between about 0% and about 40% flyash, between about 25% and about 41% sand, between about 1% and about 3%fiber, between about 0% and about 4% acrylic polymer, between about 0.4%and about 0.5% superplasticizer, between about 12% and about 15 % water,between about 0% and about 1% water proofing agent, between about 0% andabout 3% color 42.3% sand, about 1.0% polypropylene fiber, about 0.1%superplasticizer and about 14.3% water, and between about 0% and about3% color (4#/94# of C+F/A) and between about 0% and about 3% color(0.5#/94# of C+FA).

In other more detailed features of the invention, the sandwich panel mayinclude an opening formed by first and second jamb beams that extendbetween the lower border beam and the upper border beam, and by a sillbeam and a header beam that each extend between the first and secondjamb beams. The first and second jamb beams are substantially parallelwith the first and second end beams and the sill beam and the headerbeam are each substantially parallel with the lower and upper borderbeams.

Other embodiments of the invention include a cast wall panel that ismodular and, depending on size, includes one or a plurality precastboots that are integrated with the panel. Polypropylene or polyvinylalcohol fibers are dispersed throughout the panel thereby providing awall panel with increased strength. The more strength needed toreinforce the panel, the more fibers that can be added. Specifically,the deflection strength of the panel is significantly higher than itwould be if the reinforcing fibers were not used. Also, vibrations arereduced due to the fibers, thereby improving acoustic characteristics.The fibers serve a combination of purposes, i.e., insulation, structuraland form material

These and other aspects of the invention will be better understood bythose of skill in the art with reference to the following drawingswherein like numbers represent like elements throughout the severalviews.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate embodiments of the presentinvention and, together with the description, serve to explain theprinciples of the invention.

FIG. 1 is a perspective view of a fiber-reinforced sandwich panel,according to the present invention.

FIG. 2 is a cross-sectional elevation view of the fiber-reinforcedsandwich panel of FIG. 1, showing a frame structure behind a face panel.

FIG. 3 is a cross-sectional plan view of the fiber-reinforced sandwichpanel of FIG. 1.

FIG. 4 is a perspective view of a fiber-reinforced sandwich panel havingan opening, according to the present invention.

FIG. 5 is a cross-sectional elevation view of the fiber-reinforcedsandwich panel of FIG. 4, showing a frame structure behind a face panel.

FIG. 6 is a cross-sectional plan view of the fiber-reinforced sandwichpanel of FIG. 4, showing a jamb of the opening.

FIG. 7 is a cross-sectional elevation view of the windowedfiber-reinforced sandwich panel of FIG. 4, showing a header of theopening.

DETAILED DESCRIPTION

With reference to FIGS. 1-3, the present invention resides in afiber-reinforced sandwich panel 10 having a lightweight andcost-effective construction. The sandwich panel is formed of a uniquecementitious material that allows it to be insect resistant andgenerally impervious to moisture. Rigid blocks 12 of insulation areembedded in the sandwich panel to provide a desired insulation value tothe sandwich panel and to define a support frame 14 that meets desiredstructural parameters for the sandwich panel.

The sandwich panel 10 may be constructed by pouring a first layer of thecementitious material into a mold (not shown) for forming a casting facepanel 15. The rigid insulation blocks 12 are then placed on the firstlayer. The blocks are sized to define the size of ribs 16 between theblocks and border beams, 18, 20, 22 and 24, around the edge of thesandwich panel. Small nylon spacers (not shown) are placed between themold and the insulation blocks to define the thickness of the castingface panel.

Optionally, though not necessary, reinforcing bars 26 may be placed inthe spaces for the border beams that surround the insulation blocks foradding structural strength to the border beams and the sandwich panel.The reinforcing bar 26 may extend a few inches outside of the sandwichpanel to assist in-handling the sandwich panel and for attaching thepanel to other structural members. The ribs 16 extend between the upperborder beam 18 and the lower border beam 20 and are substantiallyparallel with the border beams, 22 and 24, at the ends of the sandwichpanel. The ribs 16 provide support to the face panels, 15 and 28, andassist in the load bearing characteristics of the sandwich panel.

After placement of the insulation blocks 12 on the first layer,additional cementitious material is poured between, surrounding, andover the blocks to form the border beams, 18, 20, 22 and 24, and theribs 16. The cementitious material that is poured above the blocks formsan upside face panel 28. Accordingly, the cementitious material formsthe face panels 15 and 28, and the support frame 14. After the sandwichpanel has initially cured, it is removed from the mold.

The sandwich panel 10 may have a wide variety of configurations for thesize of the beams, 18, 20, 22 and 24, the width and spacing of the ribs16, and the thickness of the casting face 15 and upside face panel 28. Arepresentative sandwich panel may have a width of 16 feet (ft.), aheight of 10 ft., and a thickness of 4.25 inches (in.). In conjunctionwith the sandwich panel thickness of 4.25 in., the beams each may have awidth of 4 in., and the ribs may each have a width of 2.5 in. Thespacing between the first end border beam 22 and the first adjacent ribof the wall panel may be 18 in. Similarly, the spacing between thesecond end border beam 24 and the first adjacent rib may be 18 in. Thespacing between the ribs may be 26 in. on center.

The cementitious material is reinforced using glass, synthetic, orsimilar fibers, to provide added structural strength to the sandwichpanel 10. A representative composition by weight (uncured) for thecementitious material is provided by the following table: TABLE 1 (% byweight - uncured cementitious material) Material Preferred RangePortland cement    19-41% Fly ash  0%-40% Sand 25%-41% Fiber 1%-3%Acrylic polymer 0%-4% Superplasticizer 0.4%-0.5% Water 12%-15% Waterproofing agent Preferably Xypex ® (2% of C) 0%-1% Color 4#/94# of C +F/A 0%-3% 0.5#/94# of C + F/A 0%-3%

The polyfiber may be polypropylene fiber or polyvinyl alcohol fiber cutto lengths of about 0.5 in. to 1.5 in. before mixing with the othermaterials. The superplasticizer may be Rheobuild® 3000FC, available fromMaster Builders, Inc. or Cleveland, Ohio. The Water proofing agent maybe Xypex® (2% of C). Other formulations for the cementitious materialare described in U.S. Pat. No. 6,073,410, titled STRUCTURE ANDFORMULATION FOR MANUFACTURE OF PREFABRICATED BUILDINGS. U.S. Pat. No.6,073,410 is incorporated herein by reference. A polymer may be added tothe mix or sprayed on the poured sandwich panel 10 to assist hydrationof the cementitious material during cure under low humidity conditionsor to enable early handling of the panel. Under controlled environmentalconditions, the polymer may be eliminated.

With reference to FIGS. 4-7, the fiber-reinforced sandwich panel 10 ofthe invention may have an opening 30 for a window or similar passage. Asshown in FIG. 5, the opening is surrounded by a header beam 32, a sillbeam 34, and first and second jamb beams, 36 and 38. The first andsecond jamb beams provide support for the upper border beam 18, theheader beam 32, and the sill beam 34. Further, the first and second jambbeams, the header beam, and the sill beam may be reinforced with bars 26to provide additional structural strength surrounding the opening in thesandwich panel.

A representative sandwich panel 10 with an opening 30 may have height of10 ft., a width of 16 ft., and a thickness of 4.625 in. The casting facepanel 15 and the upside face panel 28 may each have a thickness of 0.625in. The opening in the sandwich panel may have a width of 8 ft. and aheight of 4 ft., with the bottom of the opening being 2.5 ft. the fromthe bottom of the sandwich panel. Each rib 16 may have a thickness of2.5 in. and may be spaced between the respective end border beam, 22 or24, and respective jamb beam, 36 or 38, by 24 in.

The fiber-reinforced cementitious material allows the relatively thincasting face panel and upside face panel 28 to have a relatively highstrength. The insulation blocks 12 provide a high insulation value tothe sandwich panel 10. The sandwich panel has an appearance andimpression similar to that of a concrete structure. The configuration ofthe beams and ribs, and the placement of the reinforcing in the beams,allows the frame 14 of the sandwich panel to have sufficientload-bearing capacity to support a roof structure, additional floorlevel, or the like. Accordingly, the fiber-reinforced sandwich panel ofthe present invention provides a cost effective and relativelylightweight, insulated panel for the construction of prefabricatedstructures or the like.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, it should be understood theinvention may be implemented through alternative embodiments within thespirit of the invention. Thus, the scope of the invention is notintended to be limited to the illustration and description in thisspecification, but is to be defined by the appended claims.

1. A sandwich panel, comprising: a first face panel having a firstpredetermined thickness and being formed of a fiber reinforcedcementitious material; the cementitious material having a composition ofcement, sand, fiber, a superplasticizer, and water, a second face panelhaving a second predetermined thickness and being formed of the samefiber reinforced cementitious material as the first face panel; and asupport frame for supporting the first and second face panels in aspaced apart configuration, the support frame being formed of the samefiber-reinforced cementitious material and being continuous with thecementitious material of the first and second face panels; and aninsulation material embedded in the sandwich panel that defines astructure of the support frame;
 2. A sandwich panel as defined in claim1, wherein the first predetermined thickness is between about 0.25inches and about 2.0 inches and the second predetermined thickness isbetween about 0.25 inches and about 2.0 inches.
 3. A sandwich panel asdefined in claim 2, wherein the sandwich panel has a height greater than4 feet, a width greater than about 4 feet, and a thickness between about2.5 and about 8 inches.
 4. A sandwich panel as defined in claim 1,wherein the support frame comprises an upper border beam, a lower borderbeam, and first and second border beams that encompass the insulationmaterial.
 5. A sandwich panel as defined in claim 4, wherein the supportframe comprises one or more ribs having a length extending between thelower border beam and the upper border beam, and being substantiallyparallel with the first and second end beams, and coupling the first andsecond face panels along the length of the ribs.
 6. A sandwich panel asdefined in claim 5, wherein the sandwich panel has a thickness ofbetween about 2.5 inches and about 8.0 inches, the beams each have awidth of between about 2 inches and about 6 inches, and the ribs eachhave a width of between about 2 inches and about 6 inches.
 7. A sandwichpanel as defined in claim 4, wherein a tensile strength and acompressive strength of each border beam can each be increased byincluding a reinforcing bar.
 8. A sandwich panel as defined in claim 7,wherein the panel includes a reinforcing bar.
 9. A sandwich panel asdefined in claim 4, wherein the sandwich panel includes an openingformed by first and second jamb beams extending between the lower borderbeam and the upper border beam, and being substantially parallel withthe first and second end beams, by a sill beam extending between thefirst and second jamb beams and being substantially parallel with thelower and upper border beams, and by a header beam extending between thefirst and jamb beams and being substantially parallel with the lower andupper border beams.
 10. A sandwich panel as defined in claim 9, whereineach beam is strengthened by a reinforcing bar.
 11. A sandwich panel asdefined in claim 1, wherein the insulation material comprises at leastone rigid block of insulation.
 12. A sandwich panel as defined in claim11, wherein the at least one rigid block of insulation is comprised ofpolystyrene.
 13. A sandwich panel as defined in claim 11, wherein the atleast one rigid block of insulation is comprised of polyurethane.
 14. Asandwich panel as defined in claim 1 wherein the cementitious materialis comprised of polyvinyl alcohol fibers.
 15. A sandwich panel asdefined in claim 1 wherein the cementitious material is comprised ofpolypropylene fibers.
 16. A sandwich panel as defined in claim 1 whereinthe composition of the cementitious material further includes a firstcolor that is 4#/94# of C+F/A and a second color that is 0.5#/94# ofC+F/A.
 17. A sandwich panel as defined in claim 1 wherein thecomposition of the cementitious material further includes fly ash.
 18. Asandwich panel as defined in claim 1 wherein the composition of thecementitious material further includes a waterproofing agent.
 19. Asandwich panel as defined in claim 1 wherein the composition of thecementitious material further includes an acrylic polymer.
 20. Asandwich panel, comprising: a first face panel having a firstpredetermined thickness and being formed of a fiber reinforcedcementitious material; the cementitious material having a composition byweight before cure of between about 19% and about 41% cement, betweenabout 0% and about 40% fly ash, between about 25% and about 41% sand,between about 1% and about 3% fiber, between about 0% and about 4%acrylic polymer, between about 0.4% and about 0.5% superplasticizer,between about 12% and about 15% water, between about 0% and about 1%waterproofing agent, between about 0% and about 3% color that is 4#/94#of C+F/A, and between about 0% and about 3% color that is 0.5#/94# ofC+F/A; a second face panel having a second predetermined thickness andbeing formed of the same fiber reinforced cementitious material as thefirst face panel; and a support frame for supporting the first andsecond face panels in a spaced apart configuration, the support framebeing formed of the same fiber-reinforced cementitious material andbeing continuous with the cementitious material of the first and secondface panels; and an insulation material embedded in the sandwich panelthat defines a structure of the support frame;